1. Field of the Invention
The invention relates to a method for layout of a monolithic chip with multi-sensors, and in particular, to a method for fabricating a monolithic chip with multi-sensors and readout circuit using standard IC process. The chip is capable of sensing pH, temperature and photo-intensity simultaneously. Additionally, the invention can achieve the objects of mass production, high yield and low cost, without additional process but the standard process.
2. Description of the Related Art
A glass electrode is typically used as an ion-sensing electrode. However, the glass electrode has the disadvantages of non-miniaturizable measurement, easy damage and portable inconvenience. Piet Bergveld introduced an ion sensitive field effect transistor (ISFET) in 1970. The ISFET has the advantages of providing pH measurement, compatible with the standard CMOS process, high input impedance and low output impedance, miniaturization for a minute solution measurement, and fast response. Therefore, the ISFET has been widely studied and applied in pH sensor miniaturization and biomedicine fields.
However, existing measurements for ISFET pH sensors have found that temperature and environment light could affect ISFETs in practical applications due to the open-gate design.